Until quite recently, pneumatic apparatuses such as pressure regulators, air filters, or lubrifiers were made of metal.
Replacing the metal with plastic material leads to a problem being posed in the provision of connecting clamps.
It is insufficient just to thread the plastic material wall of the apparatus body, since the plastic material is not hard enough, and the thread would be damaged after disassembling a few times. One suggestion has been to put metal inserts in the orifices of the connection, but this solution is expensive.
Preferred embodiments of the present invention provide a connecting clamp which is robust and cheap.